In an optical fingerprint system, due to interference of ambient light, chip dark current, temperature and other factors, the fingerprint imaging performance is significantly affected, and thus the stability and security of the optical fingerprint system are seriously affected.
At present, in order to enhance an anti-interference ability of the optical fingerprint system, the major solutions include optimizing a chip design to reduce an impact of the chip dark current; or, obtaining an impact of these external interference in a typical environment, and then performing calibration in actual imaging; or, designing a dark background light path.
However, these methods may only reduce the impact caused by some of interference factors, for example, optimizing the chip design may only reduce the impact of the chip dark current, but may not reduce the impact of the ambient light; if calibration is performed on actual fingerprint image according to the impact of the external interference in the typical environment, inaccurate calibration may occur for scenarios that differ a lot from the typical environment.
Therefore, a method for acquiring a fingerprint, which is capable of reducing the interference of the ambient light, chip dark current, temperature or other factors on the fingerprint image, is needed.